how to loop through all the combinations of this list

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I have a

C#

List<List<int>>

with no idea of how many integers are there in each list or how many lists are there.

what type of loop could i use so that i get all the possibilities of the integers such that I get one integer from each List.

For example:
Here is the list of integers (each line representing a List of int and the entire thing representing the List of List of int)

1,3
2,4
3,5,6

all combinations are : (1,2,3), (1,2,5), (1,2,6), (1,4,3),(1,4,5),(1,4,6),(3,4,3),(3,4,5),(3,4,6),
(3,2,3),(3,2,5),(3,2,6) which i would like as the result

I prefer to get the combinations as a List of List of int.

Posted 11-Feb-14 23:03pm

rohith naik

Updated 12-Feb-14 4:52am

v3

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rohith naik 12-Feb-14 11:36am

I have solved this by using a very complex and bad algorithm. That is why I have not posted it here. If anyone does want it please let me know.

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V. · Answer 1 · 2014-02-12T00:15:00

If it's just a list inside a list, why not use a double for loop?

C#

List<list><int>> mydoublelist = new List<list><int>>();
List<int> myintlist = new List<int>();

for(int i = 0; i < mydoublelist.Count; i++){
  List<int> mysinglelist = mydoublelist[i];
  for(int j = 0; j < mysingleist.Count; j++){
    myintlist.Add(mysinglelist[j]);
  }
}
</int></int></int></int></list></int></list>

Notes:
- I think there is an AddRange method wich would avoid the second loop. You could do something like myintlist.AddRange(mysinglelist); instead.
- If you need unique integers the AddRange won't work and you'll need the second loop. Check for the mysingelist.Contains( ... ) method.

hope this helps.

Silent Guardian · Answer 2 · 2014-02-12T01:44:00

Solution 4

Here is a solution.
Add all elements in each list into a single list,then permute it.

C#

//Outer is your main list which contain other lists
foreach (List<int> i in Outer)NewList.AddRange(i);
</int>

Now permute NewList collection.
Here is a list of permutation articles in codeproject. use any1 of them.

Posted 12-Feb-14 1:44am

Silent Guardian

Comments

rohith naik 12-Feb-14 10:50am

we need only one element from a row. You method will yield ones with many elements from one row.

Silent Guardian 12-Feb-14 11:28am

out of curiosity, what does your application do?

rohith naik 12-Feb-14 11:31am

Basically I am using a mod in Solr to return the hit words back to me and trying to map the words back to the original text. Unfortunately This is as much info I can cram into a comment. This is kind of like a sub - sequence problem.